High acrylonitrile polymer solutions containing 2, 4, 6-trichlorophenol



United States Patent 3,282,878 HIGH ACRYLONITRILE POLYMER SOLUTIGNSC(BNTING 2,4,6-TRIHLOROPHENUL Fred J. Lowes, Jrx, Midland, Mich,assignor to The Dow Chemical Company, Midland, Mich, a corporation ofDelaware No Drawing. Filed July 26, 1965, Ser. No. 475,011

11 Claims. (Cl. 260-296) This application is a continuation-in-part ofcopending application Serial No. 177,217, filed March 5, 1962, nowabandoned.

This invention relates to compositions of matter that are especiallyadapted for use in spinning acrylonitrile polymer synthetic textilefibers or the like structures having long-lasting bacteriostaticproperties. It relates more particularly to spinnable solutions of suchpolymers in concentrated aqueous salt solutions having minor buteffective amounts of 2,4,6-trichlorophenol dissolved therein. Theinvention is also concerned with shaped articles, especially filamentarystructures, having bacteriostatic properties, and to a process forpreparing such compositions and articles.

The word solution is used herein in the connotation commonly employed inthe acrylonitrile polymer spinning art.

Polyacrylonitrile and many of the fiber and film-forming copolymers ofacrylonitrile may advantageously be fabricated by a wet spinning processwherein the polymer composition is extruded from compositions of thepolymer in polyacrylonitrile-dissolving aqueous saline solvents,particularly aqueous solutions of zinc chloride and its salineequivalents. Such a procedure, as is well known in the art, isoftentimes referred to as salt-spinning with the fibers (or other shapedarticles) obtained thereby being salt-spun. In salt-spinning, thefiber-forming, aqueous saline spinning solution or other composition ofthe polymer is extruded during the spinning operation into anon-polymer-dissolving coagulation liquid, or spin bath, whichfrequently is a solution of the same salt or salts as are in thespinning solution.

Acrylonitrile polymers (including fiber-forming copolymers),particularly polyacrylonitrile, that are saltspun in the referred-tomanner are generally formed as aquagel intermediates. Such intermediateshave a waterswollen or hydrated structure prior to their being finallyirreversibly dried to the desired, characteristically hydrophobic,product.

Advantageously, the aquagel structures of polyacrylonitrile and otherfiber and film-forming acrylonitrile polymers may be derived by theextrusion of a solution of the acrylonitrile polymer that is dissolvedin an aqueous zinc chloride saline solvent therefore into andcoagulation in an aqueous coagulating spin bath. It is usually desirablefor zinc chloride to be at least the principal (if not the entire)saline solute in the aqueous saline solvent solution.

If preferred, however, various of the saline equivalents for zincchloride may also be employed in the aqueous saline solvent medium forthe spinning solution and the coagulating bath utilized. These zincchloride equivalents, as is well known, include various of thethiocyanates (such as calcium thiocyanate) lithium bromide and the saltsand salt mixtures that are solvent members of the so-called lyotropicseries as are disclosed, among other places, in US. 2,140,921;2,425,192; 2,648,592; 2,648,593; 2,648,646; 2,648,648; and 2,648,649.

Fibers produced from acrylonitrile polymers have excellent physicalproperties but do not have the inherent ability to inhibit the growth ofbacteria. The textile industry is particularly interested in a fibrousmaterial useful for the production of blankets, carpeting and the like,

which has the desirable properties of polyacrylonitrile or fiber-formingcopolymers containing at least weight percent of acrylonitrile in thepolymer molecule and in addition has the ability to inhibit the growthof bacteria and to destroy existing bacteria. It is also highlydesirable to prepare heat shrinkable, flexible films useful for bottleclosures and the like applications which have long-lastingbacteriostatic properties.

Fabricated acrylonitrile polymer film, textile fibers and likefilamentous articles derived from salt-spinning processes aregenerically described as being capable of lying substantially in asingle plane, having at least one major dimension, and at least oneminor dimension less than about 0.1 inch, said articles beingcharacterized by having orientation of the molecules parallel to oneanother and to a major axis of the article.

The foregoing statement of the problem has referred to fibers and films,and the invention will be illustrated with respect to fibers. Theproblem is more general, however, and applies to the definedcompositions in the form of sheets, tubes, rods and molded articles aswell as films, fibers and other filaments.

It is the primary object of the present invention to providecompositions of matter especially adapted for use in spinning syntheticfilms and textile fibers or like structures of high acrylonitrilepolymers (i.e. those having at least 85 weight percent of polymerizedacrylonitrile in the polymer molecule) having long-lastingbacteriostatic properties.

'A further object is to provide shaped articles from the composition ofthe present invention which have longlasting bacteriostatic properties.

A still further object is to provide a process of producing thecompositions and articles of the present invention.

Other and related objects will become evident from the followingspecification and claims.

In accordance with the present invention high acrylonitrile films andtextile fibers having long-lasting bacteriostatic properties areproduced from a polymeric spinning solution comprising (1) anacrylonitrile polymer containing in the polymer molecule at least about85 weight percent of acrylonitrile said polymer dissolved in an aqueoussaline solvent solution, preferably where zinc chloride is the principal(if not entire) saline solute, and (2) dissolved therein at least about10 weight percent, based on said fiber-forming polymer weight of2,4,6-trichlorophenol.

The acrylonitrile polymer employed in practice of the present inventionis, advantageously, polyacrylonitrile, although, as is readily apparent,any of the well-known fiber and film-forming copolymers thereof thatcontain, polymerized in the polymer molecule, at least 85 weight percentof acrylonitrile with at least one other ethylenically unsaturatedmonomer, that is copolymerizable with acrylonitrile may, beneficially,be utilized. The acrylonitrile polymer employed is soluble in an aqueoussaline solvent which, usually, has therein at least about 50-60 weightpercent of zinc chloride or its saline equivalents. US. 2,776,946, amongmany other reference sources, exemplifies many of the monomers which maybe copolymerized or interpolymerized with acrylonitrile to producebinary or ternary acrylonitrile copolymers that are useful in thepractice of the invention.

The compound 2,4,6-trichlorophenol is a readily available material, thepreparation of which is well known to those skilled in the art.

The 2,4,6-trichlorophenol is compatible with the acrylonitrile polymersdefined herein when incorporated in said polymers by the process of thepresent invention.

It has also been found that 2,4,6-trichlorophenol must be present in thepolymer solution in a minimum amount of about 10 weight percent based onthe weight of the a acrylonitrile polymer if the objectives of theinvention are to be attained. The permissible proportion depends on thelimit of its compatibility with the aqueous saline solution, as well asthe polymeric material contained therein. The maximum limit is generallyabout 20 weight percent, based on the weight of the acrylonitrilepolymer.

The amount of 2,4,6-trichlorophenol (hereafter called bacteriostaticagent) present in shaped articles produced from salt-spun acrylonitrilepolymers is dependent upon, and approximately in the same ratio as, theamounts of the bacteriostatic agent incorporated in the spinningsolution.

The bacteriostati-c agent may be suitably admixed with the polymericspinning solution by stirring at room temperature.

It has been found that the bacteriostatic agent is compatible with theacrylonitrile polymers defined herein when used in the prescribedamounts, and is substantially waterinsoluble. The above combination ofdesirable properties prevents excessive extraction of the bacteriostaticagent from the polymer during coagulation of the polymer solution in anaqueous non-polymer-dissolving saline medium, and during subsequentwater washing of the resulting aquagel and shaped article producedtherefrom.

Shaped articles produced from acrylonitrile polymers by the process ofthe present invention do not significantly lose their bacteriostaticproperties even after repeated laundering.

It will be appreciated by those skilled in the art that various othermaterials can be added to the compositions of the present invention.Such materials include, for example, plasticizers, lubricants, dyeassistants, dyes and pigments.

The following example, wherein all parts and percentages are to be takenby weight, illustrates the present invention but is not to beconstructed as limiting its scope.

Example I In each of a series of experiments, separate charges of about35 grams of a solution consisting of percent polyacrylonitrile, 54percent zinc chloride, and 36 percent water, all based on the totalweight of the solution, were separately placed in one of several glassbottles. Thereafter, to one of the solutions was added, with stirring,10 weight percent of 2,4,6-trichlorophenol; to another solution wasadded, with stirring, 10 weight percent of 2,4,5-trichlorophenol; and toyet another solution was added 10 weight percent of o-diphenylphenol.Each of the samples was then placed in a standard laboratory ovenmaintained :at a temperature of about 80 C. until each of such sampleswas free from bubbles.

Each of the bubble-free spinning solutions was then ingel tow andcollected, and the resulting aquagel tows water washed untilsubstantially free of zinc chloride.

There were thereby separately obtained individual aquagel filament towscontaining about 1 part water for each part of polymer therein. Theaquagel filament tows were then each separately oriented by beingstretched to a length of about 10 to 12 times their original extrudedlength and allowed to :air dry at normal room temperatures.

The filament tows were then finally irreversibly dried for about 5minutes at about 140 C.

Each dried filament tow was then individually placed on the surface of anutrient agar contained in a conventionally used Petri dish or plate,which agar had been previously inoculated with Staphylococcus aureus bysmearing the surface of the nutrient agar with a swab from a brothculture of Staphylococcus aureus. The dishes were then set aside forincubation at a temperature between about 30 C. and 37 C. Afterincubation, the plates were examined to determine the extent of controlof the growth of the organisms of Staphylococcus aureus. Examination ofthe plates supporting the filament tows containing 2,4,6-trichlorophenolshowed a zone of about 1 mm. immediately surrounding said tows which wasfree of the growth of the organisms of Staphylococcus aureus.Examination of a series of plates supporting individual filament towscontaining 2,4,5-trichlorophenol or o-phenylphenol showed that in allinstances, a heavy outgrowth of colonies of Staphylococcus oureus waspresent in the zone immediately surrounding said tows.

The unexpected effectiveness of the bacteriostatic agent of the presentinvention, when utilized in combination with a fiber and film formingacrylonitrile polymer as herein described, is illustrated by thefollowing tests wherein the bacteriostatic properties of each of theabove referred to compounds were individually determined. In such teststhe materials evaluated were individually dispersed in nutrient agar toprepare individual Petri dishes of agar medium containing from about 10to parts per million by weight of one of said compounds. The surfaces ofthese dishes were inoculated with one of several organisms, ashereinafter identified, by smearing the surfaces with a swab from abroth culture of such organism. At the same time, Petri dishescontaining untreated agar media were similarly inoculated from the samebroth culture, the dishes were set aside for incubation at a temperatureof 30 C., for 72 hours. After incubation, the plates were examined todetermine the control of the growth of the organism. Examination of thetreated plates provided the data appearing on the following Table I.

TABLE I Bacteriostatic Agent Appearance of Agar Media Organism TestedFollowing Incubation Type Cone ppm None Heavily overgrown. 2, 4,5-tnchlorophenoL. 10 Do. Staphylococcus aureus 0 50 Essentially free ofgrowth.

2, 4, fi-trichl0rophenol 10 Heavily overgrown. do 50 Essentially tree ofgrowth. None Heavily overgrown. 2, 4, 5-triehlorophenol 10 Do.Salmonella typhosa do 50 Essentially free of growth.

2, 4, otriehlorophenol" 10. Heavily overgrown. do 50 Essentially free ofgrowth. None Heavily overgrown. Aerobact aerogenes 2, 4,5-triehl0r0phenol 5O Essentially free of growth.

do 50 Heavily overgrown.

dividually extruded through a spinnerette having about 300 orifices(ea-ch orifice having a diameter of about 3 mils), into an aqueousnon-polymer-dissolving zinc chloride coagulating bath. The aquagelsindividually formed therein were separately spun into a multiplefilament aqua- It will be seen by reference to the data of Table I thatthe comparative materials, as specifically identified therein, aregenerally at least as effective as bacteriostatic agents per so, as thebacteriostatic agent employed for the purposes of the present invention.

Similar good results as previously illustrated herein are obtained usingany concentration between about weight percent to 20 weight percent ofpolymer weight of 2,4,6-trichlorophenol.

In addition, similar good results are obtained when fiber andfilm-forming acrylonitrile polymers containing at least 85 weightpercent of polymerized acrylonitrile and up to weight percent of one ormore of such copolymerizable materials as vinyl chloride, vinyl acetate,methyl and other alkyl acrylates or methacrylates, the vinyl pyridines,allyl alcohol and many others Well known to those skilled in the art,are admixed with the prescribed amounts of 2,4,6-trichlorophenol.

What is claimed is:

1. Bacteriostatic composition comprising a spinnable solution of (1) afiber-forming acrylonitrile polymer which contains in the polymermolecule at least about 85 Weight percent of acrylonitrile, any balancebeing another monoethylenically unsaturated monomeric materialcopolymerizable with acrylonitrile, (2) an aqueous saline solvent forpolyacrylonitrile; said solvent having additionally dissolved therein 3)at least about 10 weight percent based on said fiber-forming polymerweight of 2,4,6-trichlorophenol.

2. The composition of claim 1, wherein the 2,4,6-trichlorophenol ispresent in amounts between about 10 and Weight percent based on theweight of said fiber-forming polymer.

3. The composition of claim 1, wherein said fiber-forming polymer ispolyacrylonitrile.

4. The composition of claim 1, wherein said aqueous saline solvent is asolution of zinc chloride.

5. In the process of producing bacteriostatic articles from a spinningsolution of a fiber-forming acrylonitrile polymer which contains in thepolymer molecule at least about 85 weight percent of acrylonitrile, anybalance being another monoethylenically unsaturated monomeric materialcopolymerizable with acrylonitrile, which polymer is dissolved as aspinnable composition in an aqueous saline solvent for saidfiber-forming polymer; the

step of dissolving in said spinning solution at least about 10 weightpercent, based on the weight of said fiber-forming polymer in saidspinning solution, of 2,4,6-trichlorophenol.

6. The process of claim 5, wherein the 2,4,6-trichlorophenol is presentin amounts between about 10 and 20 weight percent based on the weight ofsaid fiber-forming polymer.

7. The process of claim 5, wherein said fiber-forming polymer ispolyacrylonitrile.

8. The process of claim 5, wherein said aqueous saline solvent is asolution of zinc chloride.

9. A polymeric filament having bacteriostatic properties, comprised of(1) a fiber-forming acrylonitrile polymer which contains in the polymermolecule at least about weight percent of acrylonitrile, any balancebeing another monoethylenically unsaturated monomeric materialcopolymerizable with acrylonitrile, and (2) dispersed throughout atleast about 10 weight percent based on said fiber-forming polymer weightof 2,4,6-trichlorophenol.

10. The filament of claim 9, wherein the 2,4,6-trichlorophenol ispresent in amounts between about 10 and 20 weight percent based on theweight of said fiber-forming polymer.

11. The filament of claim 9 wherein said fiber-forming polymer ispolyacrylonitrile.

References Cited by the Examiner UNITED STATES PATENTS 2,460,377 2/1949Capiro l06l86 2,533,224 12/1950 Cresswell 26029.6 2,763,636 9/1956 Davis26029.6 2,873,263 2/1959 Lal 26085.5 2,925,361 2/ 1960 Bollenback 260623MURMY TILLMAN, Primary Examiner.

N. F. OBLON, Assistant Examiner.

1. BACTERIOSTATIC COMPOSITION COMPRISING A SPINNABLE SOLUTION OF (1) AFIBER-FORMING ACRYLONITRILE POLYMER WHICH CONTAINS IN THE POLYMERMOLECULE AT LEAST ABOUT 85 WEIGHT PERCENT OF ACRYLONITRILE, ANY BALANCEBEING ANOTHER MONOETHYLENICALLY UNSATURATED MONOMERIC MATERIALCOPOLYMERIZABLE WITH ACRYLONITRILE, (2) AN AQUEOUS SALINE SOLVENT FORPOLYACRYLONITRILE; SAID SOLVENT HAVING ADDITIONALLY DISSOLVED THREIN (3)AT LEAST ABOUT 10 WEIGHT PERCENT BASED ON SAID FIBER-FORMING POLYMERWEIGHT OF 2,4,6-TRICHLOROPHENOL.